No, there are no tags anything like that, just regular search.

I switched to miniflux months ago and I’m pretty happy with it. Supports categories as well.

I do host my own mailserver for multiple years now without any issues.

I’m using https://docker-mailserver.github.io/docker-mailserver/latest/ on a rented server, not at home. I recently added DKIM and I check my setup via https://mxtoolbox.com and the like in irregular intervals to see if I can improve something.

The only downside I see is spam filtering, which obviously works better with GMail if the whole world population does the filtering for you. But the included SpamAssassin setup does work and catches most of the spam. I do check for false positives/negatives very regularly and have training folders set up so I can easily move messages into the SA training.